1. Field of the Invention
This invention relates to a voltage controlling method for a head mounted display unit and a head mounted display apparatus, and more particularly to a voltage controlling method and apparatus for a portable head mounted display unit which is driven by a battery and can be used for a long period of time with low power consumption.
2. Description of the Related Art
A conventional head mounted display apparatus as shown in FIG. 5, has a form like eyeglasses and is mounted on the head of a user with a pair of temples thereof suspended on the ears of the user such that an image displaying housing is positioned in front of the eyes of the user.
FIG. 12 shows a construction of an image displaying housing of such a conventional head mounted display apparatus as mentioned above. Referring to FIG. 12, the image displaying housing 10 includes an image displaying section 11 for forming an image to be displayed, and a power supply voltage section 12 for supplying a power supply voltage to the image displaying section 11 and other components of the image displaying housing 10 which are not particularly shown in FIG. 10.
The image displaying section 11 includes a .gamma. correction section 13 for receiving an image signal and performing .gamma. correction of the received image signal, an LCD driver section 14 for converting a signal from the .gamma. correction section 13 into an ac driving signal, an LCD panel 15 for forming and displaying an image based on the signal from the LCD driver section 14, a back light 16 for irradiating light upon the LCD panel 15 from the back, and an LCD panel driving control section 17 for controlling the image to be formed.
In the image displaying section 11 which includes the components described above, if a power supply switch not shown is switched on, then a power supply voltage from the power supply voltage section 12 is supplied to the components of the image displaying section 11. Thus, when the power supply is on intentionally, the power supply voltage is supplied to all of the component circuits of the image displaying section 11 to display an image on the LCD panel 15 irrespective of whether the user looks at the LCD panel 15 of the image displaying section 11 or not.
However, even when the user intentionally looks away from the image displayed on the LCD panel, the power supply voltage is supplied to all of the component circuits of the image displaying section. Therefore, the circuit construction of the image displaying section of the conventional head mounted display apparatus has a problem in that, when the user wants to enjoy a displayed image as long as possible while the head mounted display apparatus is driven by a battery, the power supply must be switched off frequently every time.